It is conventionally well known in the art that, when a silver halide light-sensitive material containing a dye-forming coupler is exposed imagewise to light and processed with a color developing solution, an oxidant derived from a developing agent of an aromatic primary amine compound causes a coupling reaction with the dye-forming coupler to form a dye image made of such as an indophenol, indoaniline, indamine, azomethine, phenoxyazine, phenazine or dyes analogous to them.
What is required for the dye image obtained in such a manner is that it does not show discoloration or color fading even if it is stored under high temperature and/or high humidity. Additionally, what is required for the non-colored portion in a silver halide light-sensitive material (hereinafter referred to as color photographic material) is that it does not show yellow-stain (hereinafter referred to as Y-stain) due to light, heat or moisture.
However, in the case of a magenta coupler, the Y-stain in the non-colored portion due to light, heat or moisture as well as the color fading of the dye image portion due to light are extremely great, when compared to a yellow coupler or a cyan coupler, often causing troubles.
5-pyrazolones are widely used as couplers to form magenta dyes. It is a great disadvantage that dyes formed from 5-pyrazolo-5-ones have a secondary absorption in the range around 430 nm in addition to a primary absorption around 550 nm. Various attempts have been made in order to solve this disadvantage. A magenta coupler having anilino group in the third position of a 5-pyrazolone has a limited secondary absorption and is advantageous especially in obtaining a printed color image. Such a method is disclosed, for example, in U.S. Pat. No. 2,343,703 and UK Patent No.1,059,994.
However, the above-mentioned magenta couplers have a disadvantage that a shelf stability is limited, and especially, a light resistance of a dye image is significantly poor and in a disadvantageously great Y-stain in a non-colored portion.
In order to reduce the secondary absorption around 430 nm of the above-mentioned magenta couplers, the following magenta couplers have also been proposed. pyrazobenzimidazoles mentioned in U.K. Patent No. 1,047,612; indazolones mentioned in U.S. Pat. No. 3,770,447; 1H-pyrazolo [5,1-c]-1,2,4-triazole couplers disclosed in U.S. Pat. No. 3,725,067, U.K. Patents No. 1,252,418 and No. 1,334,515; 1H-pyrazolo [1,5,-b]-1,2,4-triazole couplers disclosed in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) No. 171956/1974 and Research Disclosure No. 24531; 1H-pyrazolo [1,5,-c]-1,2,3-triazole couplers disclosed in Research Disclosure No. 24626; 1-H-imidazo [1,2,-b] pyrazole couplers disclosed in Japanese Patent O.P.I. Publication No. 162548/1984 and Research Disclosure No. 24531; 1H-imidazo [1,5,-b]pyrazole couplers disclosed in Japanese Patent O.P.I. Publication No. 43659/1985 and Research Disclosure No. 24230; 1H-pyrazolo [1,5,-d] tetrazole couplers disclosed in Japanese Patent O.P.I. Publication No. 33552/1985 and Research Disclosure No. 24220. Among these examples, dyes formed from 1H-pyrazolo [5,1,-c]-1,2,4-triazole couplers, 1 H-pyrazolo [1,5,-b]-1,2,4-triazole couplers, 1H-pyrazolo [1,5,-c]-1,2,3triazole couplers, 1H-imidazo [1,2,-b] pyrazole couplers, 1H-pyrazolo [1,5,-b] pyrazole couplers or 1H-pyrazolo [1,5,-d] tetrazole couplers have a significantly smaller secondary absorption around 430 nm of wavelength, when compared with the previously mentioned dyes formed from 5-pyrazolones having an anilino group in the 3-position. This feature is very advantageous in regard to the color reproduction. Additionally, it is an advantage of such dyes that they show the significantly decreased Y-stain in the non-colored portion due to light, heat or moisture. However, azomethine dyes formed from the couplers, above, are extremely vulnerable to light. And worse, the above-mentioned dyes are easily discolored by light, significantly jeopardizing the performance of color photographic materials, especially color photographic materials for print. Consequently, such dyes have not been employed for a practical use.
In order to improve the light-resistance of magenta dye images formed from 1H-pyrazolo [5,2,-c]-1,2,4-triazole magenta couplers, a method has been proposed in Japanese Patent O.P.I. Publication No. 125732/1974, where phenol compounds for phenyl ether compounds are added to 1H-pyrazolo [5,1,-c -1,2,4-triazole magenta couplers.
However, it was revealed that such an art is not fully effective in preventing the magenta dye image, mentioned above, from fading, and that the prevention of the discoloration due to light was near-impossible.